Pregnancy & Obstetrics
Every pregnancy & obstetrics calculator on CalcEngines — each with its formula, a worked example, the standard it follows and the assumptions it makes.
3 calculators in this section
- Ovulation & Fertile Window CalculatorA predicted ovulation day and a fertile window, counted backwards from the next expected period because the luteal phase is the stable half of the cycle — with the window’s width shown first, the implantation range and an informative pregnancy-test date beside it, and the published typical-use failure rate of calendar methods stated plainly. This is a page for trying to conceive; it is not a way to avoid pregnancy.
- Pregnancy Due Date & Gestational Age CalculatorGestational age in completed weeks and days, and an estimated due date, by four separately sourced dating methods — the 280-day rule adjusted for your own cycle length, a known conception or embryo transfer date, a measured crown-rump length through either of two published equations, and a gestational age a scan already reported. The due date is printed with the days on which 37 and 42 weeks fall, because a due date on its own is the middle of a five-week window.
- Pregnancy Weight Gain Calculator (kg, by BMI)The recommended total gain for a pre-pregnancy BMI category, from the ranges the Institute of Medicine published in 2009 and the CDC republishes, apportioned to the gestational age you are at rather than compared against a 40-week total — with the first-trimester allowance kept separate from the weekly rate, the Asian-Indian BMI cut-offs shown alongside the standard ones instead of swapped in silently, and the places where the published table does not agree with itself written down rather than smoothed over.